Controlling wettability of femtosecond laser-structured titanium implant surfaces for biological cultivation

This study presents a strategy to modulate the surface wettability of titanium (Ti) and Ti alloys (Ti-6Al-4 V) through femtosecond laser structuring combined with thermal treatment for biological cultivation applications. Hierarchical micro/nano dual-scale structures were fabricated using a 520 nm femtosecond laser, producing microgrooves with a depth of 10 μm and laser-induced periodic surface structures (LIPSS) with a period of 800 nm. After laser structuring, the samples were first thermally pre-treated at 500 °C for 30 min and then subjected to subsequent thermal treatment at 150 °C and 350 °C for 2 h, while samples maintained at room temperature (RT, 25 °C) served as the control group. The results indicate that femtosecond laser-induced micro/nano structures significantly increase the reaction surface area, facilitating enhanced surface modification. Contact angle (CA) measurements reveal that Ti surfaces treated at 150 °C exhibit superhydrophobic behavior (CA = 154°), whereas treatment at 350 °C results in superhydrophilic surfaces (CA = 0°). In contrast, Ti-6Al-4 V surfaces retain hydrophobicity, with higher temperatures further enhancing this effect. Escherichia coli (E. coli) culture tests demonstrate that surface wettability strongly influences bacterial adhesion. Superhydrophobic surfaces promote bacterial attachment (682 CFU/mm²), whereas superhydrophilic surfaces significantly suppress bacterial colonization (32 CFU/mm²). These findings highlight the potential of thermally tunable wettability on laser-structured Ti surfaces for engineering implant biointerfaces in biological cultivation and antibacterial applications.